SEA → SLC Flight Reliability

Right now

Origin · SEANo disruption reported

Aviation weather is not currently a factor.

Updated 08:53 UTC

Seattle airport profile →

Destination · SLCNo disruption reported

Aviation weather is not currently a factor.

Updated 08:54 UTC

Salt Lake City airport profile →

Route reliability

July 2023 – July 2026

Route Reliability Score

82/ 100Strong

Better than 90% of comparable major US routes (4,598 compared)

Calculated from 12,345 flights. How this is calculated

On-time arrivals

83.4%

10,229 of 12,259

Cancellation rate

0.65%

80 cancelled

Median arrival delay

-6 min

Average 0.7 min

Severe delays

3.9%

60+ minutes late

Delay when late

50 min

Average, when 15+ min late

Flights analyzed

12,345

3 carriers

SEA → SLC arrives on time 83.4% of the time; the return trip, SLC → SEA, arrives on time 80.7% of the time, a 2.7-point gap between the two directions of the same city pair.

SEA → SLC spends 27.3 minutes on the ground on a 689-mile trip: 20.2 minutes from pushback to wheels-up at SEA and 7.1 minutes from touchdown to gate at SLC.

Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026

What stands out

This route has stayed remarkably steady year over year, a smaller swing than 97% of 5,368 comparable routes.

83.6% on time over the most recent 12 months (2025-08 to 2026-07), against 83.8% in the 12 months before (2024-08 to 2025-07), virtually unchanged.

Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Ranked against every other route with the same kind of figure and at least 5,368 in the comparison.

Why SEA → SLC flights are cancelled

July 2023 – July 2026

SEA → SLC cancelled 80 of 12,345 scheduled flights — about 1 in every 154. The reason filed most often was the airline, 72.5% of the cancellations coded on this route — about 1 in every 213 scheduled flights.

Share of cancellations

Airline72.5%

Weather20.0%

Air traffic7.5%

Security0.0%

Of 80 cancelled departures carrying a reason code.

What each reason means

The airline1 in 213

Crew, maintenance, aircraft cleaning, baggage or fueling: what BTS counts as within the carrier’s own control.

58 cancellations, 72.5% of the total.

Extreme weather1 in 772

Conditions the carrier judged severe enough to stop the flight: a blizzard, a hurricane, a line of thunderstorms.

16 cancellations, 20.0% of the total.

The air traffic system1 in 2,058

Airport capacity, air traffic control flow programs, heavy traffic and ordinary bad weather. A system decision, not the airline’s.

6 cancellations, 7.5% of the total.

Security—

A terminal evacuation, a security breach, screening equipment failure, or screening queues over 29 minutes.

0 cancellations, 0.0% of the total.

Reason codes are the operating airline’s own filing with US DOT, not an independent finding of fault. Ordinary bad weather is filed under air traffic, so weather’s full share is larger than its bar.

80 coded cancellations were recorded on SEA → SLC; the section appears from 50.

When it goes wrong

July 2023 – July 2026

One arrival in ten is worse than

26 min late

against a median of 6 min early

Arrived an hour or more late3.9%

Typical delay when late50 min

Cancelled0.65%

Landed somewhere else0.05%

Percentiles over 12,345 operations; cancelled and diverted flights are counted separately.

Will your connection be tight enough?

Layovers at SLC after arriving from SEA.

Connection buffer and chance of missing by layover length, SEA → SLC arrivals
Connection time	Chance of missing	Reads as
30 min	33%	Likely to miss
45 min	16%	High risk
60 min	8.8%	Some risk
90 min	3.9%	Low risk
120 min	1.9%	Low risk

This is one leg of a connection. Gate changes and the next flight's own schedule matter too. And a connection can fail before delay is even the question — this route cancels 0.65% of the time and diverts 0.05% of the time, which a late arrival never shows up in.

Chance of missing is the share of 12,259 arrivals on this route that landed later than the connection time less 30 minutes to reach the next gate.

The worst tenth of arrivals on this route land at least 26 minutes late (90th-percentile gate arrival delay), over 12,345 operations.

Any other layover length: connection checker.

Best time to fly

SEA → SLC flights departing 5–9 AM arrived on time 92.5% of the time, against 76.6% for 3–6 PM departures, a gap of 15.9 percentage points.

By day and hour

On-time arrival rate for each weekday and scheduled departure hour, in local time at the departure airport (SEA).

Hour of departure matters more than day of the week: hourly averages sit a typical 6.7 points from the route-wide rate, weekday averages 1.9 points.

On-time arrival rate for SEA to SLC by weekday and scheduled departure hour, local time. Each button reads out one slot.
Hour	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday	Sunday
5 AM–6 AM
6 AM–7 AM
7 AM–8 AM
8 AM–9 AM
9 AM–10 AM
10 AM–11 AM
11 AM–12 PM
12 PM–1 PM
1 PM–2 PM
2 PM–3 PM
3 PM–4 PM
4 PM–5 PM
5 PM–6 PM
6 PM–7 PM
7 PM–8 PM

On-time rate, % · stronger color, fewer on time

72–75
76–79
80–83
84–87
88–91
92–95
96–99

Fewer than 120 flights, not scored

Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · On time is arrival within 15 minutes of schedule. Cells round to whole percentages; the table shows one decimal.

No slot is named best or worst: too few reach 500 flights. Departures after 8 PM (698 flights) are not drawn: no slot in those hours has enough flights to score.

View as tableHide table

On-time arrival rate (%) with flights beneath, by scheduled departure hour and weekday for SEA to SLC. A dash means fewer than 120 flights, which are not scored.
Hour	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday	Sunday
5 AM–6 AM	95.6% on time161 flights	95.0% on time161 flights	95.7% on time161 flights	96.3% on time161 flights	96.2% on time161 flights	96.9% on time161 flights	95.7% on time161 flights
6 AM–7 AM	47 flights, too few to score	37 flights, too few to score	38 flights, too few to score	45 flights, too few to score	47 flights, too few to score	35 flights, too few to score	47 flights, too few to score
7 AM–8 AM	92.8% on time182 flights	92.8% on time152 flights	91.3% on time152 flights	92.7% on time180 flights	89.9% on time181 flights	87.3% on time166 flights	89.0% on time148 flights
8 AM–9 AM	47 flights, too few to score	45 flights, too few to score	47 flights, too few to score	49 flights, too few to score	48 flights, too few to score	40 flights, too few to score	50 flights, too few to score
9 AM–10 AM	89.9% on time170 flights	83.8% on time160 flights	89.9% on time159 flights	84.5% on time174 flights	86.0% on time171 flights	85.7% on time143 flights	90.4% on time170 flights
10 AM–11 AM	50 flights, too few to score	50 flights, too few to score	44 flights, too few to score	63 flights, too few to score	51 flights, too few to score	43 flights, too few to score	62 flights, too few to score
11 AM–12 PM	73.9% on time155 flights	75.8% on time157 flights	78.5% on time159 flights	72.1% on time155 flights	73.7% on time154 flights	77.2% on time150 flights	73.3% on time151 flights
12 PM–1 PM	32 flights, too few to score	24 flights, too few to score	23 flights, too few to score	26 flights, too few to score	33 flights, too few to score	22 flights, too few to score	33 flights, too few to score
1 PM–2 PM	84.2% on time215 flights	89.6% on time213 flights	84.1% on time209 flights	79.5% on time210 flights	82.0% on time215 flights	80.4% on time205 flights	79.8% on time215 flights
2 PM–3 PM	25 flights, too few to score	23 flights, too few to score	28 flights, too few to score	25 flights, too few to score	23 flights, too few to score	28 flights, too few to score	21 flights, too few to score
3 PM–4 PM	81 flights, too few to score	72 flights, too few to score	71 flights, too few to score	79 flights, too few to score	79 flights, too few to score	71 flights, too few to score	70 flights, too few to score
4 PM–5 PM	111 flights, too few to score	70 flights, too few to score	71 flights, too few to score	92 flights, too few to score	100 flights, too few to score	43 flights, too few to score	106 flights, too few to score
5 PM–6 PM	76.6% on time188 flights	83.1% on time189 flights	84.8% on time184 flights	76.0% on time184 flights	74.0% on time201 flights	79.6% on time211 flights	73.5% on time189 flights
6 PM–7 PM	89 flights, too few to score	64 flights, too few to score	64 flights, too few to score	74 flights, too few to score	90 flights, too few to score	68 flights, too few to score	82 flights, too few to score
7 PM–8 PM	82.3% on time215 flights	86.5% on time170 flights	86.2% on time174 flights	81.7% on time213 flights	77.6% on time211 flights	118 flights, too few to score	77.9% on time204 flights

By departure window

5–9 AM92.5%

9 AM–12 PM82.6%

12–3 PM82.7%

3–6 PM76.6%

6–9 PM80.1%

9 PM–5 AM89.0%

By departure hour

12 AM

3 AM

6 AM

9 AM

12 PM

3 PM

6 PM

9 PM

Why SEA → SLC runs late

July 2023 – July 2026

The airline44.5%

crew, maintenance, boarding and fueling, all within the carrier’s control

Late-arriving aircraft39.3%

the inbound aircraft was late, so this flight started late

Air traffic control13.1%

airspace and airport capacity, including weather-driven flow control

Weather3.1%

weather severe enough to stop this flight specifically

Security0.1%

screening or terminal security incidents

Share of the delay minutes US DOT attributed to each cause for SEA → SLC. Only delays of 15 minutes or more are attributed.

How this route holds up in bad weather

July 2023 – July 2026

The harder-hit end is the one the flight leaves from, where a cancellation keeps it from departing at all. Bad weather cancels 1.9 times the normal rate at SEA against barely any change at SLC. Cancelled in bad weather against normal hours: SEA 1.5% against 0.8%, SLC 0.6% against 0.6%. Flights that did leave SLC in bad weather arrived on time 71.0% of the time, against 84.8% in normal hours.

Bad weather and normal hours at the airports

Scheduled departures, July 2023 – July 2026

Departures from SEA and SLC in hours of bad weather and in normal hours
Departures from	SEA	SLC
Cancelled in bad weather	1.5%	0.6%
Cancelled in normal hours	0.8%	0.6%
Arrived on time, bad weather	75.4%	71.0%
Arrived on time, normal hours	79.3%	84.8%
Departures in bad weather	43,416	20,014

Of the carriers on this route, Delta Air Lines (1.1% cancelled against 1.6% for the other carriers at SEA) cancelled the fewest departures from SEA in bad weather and Alaska Airlines (1.8% cancelled against 1.2% for the other carriers at SEA) the most.

This route’s airlines in bad weather at SEA

All departures from SEA

Cancellation rates in bad weather at SEA for the airlines that fly SEA to SLC, against the other carriers at SEA in the same months
Airline	Bad-weather departures	Cancelled	Other carriers
Delta Air Lines	9,020	1.1%below the others	1.6%
SkyWest Airlines	6,711	1.9%above the others	1.5%
Alaska Airlines	20,261	1.8%above the others	1.2%

These are airport figures, not route figures: every scheduled departure from SEA and SLC, to any destination, in hours the weather report called bad. The airline rows count each carrier’s departures from SEA on every route.

Weather source and limits. In full: SEA (airlines), SLC, What Weather Costs Each Airport, Who Cancels More When the Weather Turns, Airports That Change Places When Weather Turns.

Airlines on this route

Carriers with at least 200 flights, by the airline that operated each one.

Airlines on this route
Carrier	Flights	On time	Cancelled	Median delay	Severe
Delta Air Lines	6,823	87.7%	0.38%	-9 min	3.3%
Alaska Airlines	3,890	78.3%	1.29%	-3 min	4.3%
SkyWest Airlines	1,441	78.1%	0.07%	-2 min	5.1%

Delta Air Lines flew 56.1% of the 12,154 flights listed. Alaska Airlines cancelled 1.29% of its flights here against 0.07% for SkyWest Airlines.

Delta Air Lines arrived on time 9.6 percentage points more often than SkyWest Airlines on this route.

Flights on this route

Flight numbers with at least 600 operations here and still on the schedule.

Flights on this route
Flight	Scheduled	Operations	On time
DL1128 Delta Air Lines	5:30 AM	849	93.0%
DL1120 Delta Air Lines	1:30 PM	785	84.9%
DL1016 Delta Air Lines	9:30 AM	757	90.7%
DL1165 Delta Air Lines	5:10 PM	721	80.2%

DL1128 (5:30 AM) arrived on time 93.0% of the time, 12.8 points more often than DL1165 (5:10 PM) at 80.2%.

Weekly and seasonal patterns

By day of week

Mon83.7%

Tue86.1%

Wed86.1%

Thu81.5%

Fri81.5%

Sat84.0%

Sun81.7%

Wednesday is historically the most reliable day and Friday the least, a gap of 4.6 percentage points.

By month

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

July is historically the weakest month and April the strongest, a spread of 10.8 percentage points.

Reliability over time

July 2023 – July 2026

24

25

26

Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 83.6% against 83.8% in the 12 months before — broadly unchanged.

Data and methodology

Calculated by FlyerIntel from 12,345 SEA → SLC flight records from the US DOT Bureau of Transportation Statistics, covering July 2023 – July 2026. Late means 15 or more minutes past scheduled arrival; cancelled and diverted flights are left out of on-time rates.

Full methodology · Data sources · Report a problem

Analysis last recomputed September 26, 2026

SEA airport SLC airport Return direction SLC → SEA

SEA→SLC

Right now

Route reliability

What stands out

Why SEA → SLC flights are cancelled

Share of cancellations

What each reason means

When it goes wrong

Will your connection be tight enough?

Best time to fly

By day and hour

By departure window

By departure hour

Why SEA → SLC runs late

How this route holds up in bad weather

Bad weather and normal hours at the airports

This route’s airlines in bad weather at SEA

Airlines on this route

Flights on this route

Weekly and seasonal patterns

By day of week

By month

Reliability over time

Data and methodology